[108.05] Formation of a Massive Black Hole at the Center of the Superbubble in M82

We performed 12CO(1 - 0), 13CO(1 - 0), and HCN(1 -
0) interferometric observations of the central region (about
450 pc in radius) of M82 with the Nobeyama Millimeter Array.
We have successfully imaged a molecular superbubble with a
diameter of ~ 210 x 140 pc (~ 14'' x 9'')
elongated perpendicular to the galactic disk. The kinetic
energy of the superbubble is ~ (0.5-2) x 1055 erg,
equivalent to the total energy of ~103-104
supernovae. The center of the superbubble is clearly shifted
from the nucleus by 140 pc. This position is close to that
of the massive black hole (BH) of > 460 Mo (Matsumoto
et al. 2000; Matsumoto & Tsuru 1999; Ptak & Griffiths
1999) and the 2.2 micron secondary peak (a luminous
supergiant dominated cluster; Joy et al. 1987), which
strongly suggests that these objects may be related to the
formation of the superbubble. Consideration of star
formation in the cluster based on the infrared data
indicates that (1) energy release from supernovae can
account for the kinetic energy of the superbubble, (2) the
total mass of stellar-mass BHs available for building-up the
massive BH may be much higher than 460 Mo, and (3) it
is possible to form the middle-mass BH of 102-103
Mo within the timescale of the superbubble. We suggest
that the massive BH was produced and is growing in the
intense starburst region. SM and HM are supported by the
JSPS Postdoctoral Fellowship for Research Abroad.